With the recent change from Bungie that lowered the score required for Tier 5 rewards to 1.2M points once you hit 450 Power, there's no real reason to grind any higher. I think this is a great change, and it makes me wonder if Bungie could reduce the seasonal Power cap from 550 to 450. It would make the climb to endgame rewards feel more rewarding and less like a pointless grind.